Ground state oxygen, O$_2$, is a triplet diradical, a property which can explain why liquid oxygen is paramagnetic and attracted to the poles of a magnet.

For this reason, to get the energy of the O$_2$ molecule, a LSD calculation is required.

1.Step

Run a single point calculation for CH$_4$, using the given input file.
Note that the file contains explicit basis sets and potential for all-electron calculations. An explanation of the basis set formats is given here: Basis Sets